This invention relates to data recorders, and, more specifically, to self-contained data recorders for use in monitoring railcar hunting.
In order to negotiate curves, a railroad wheel is tapered. When the wheel is making a curve, the side of the wheel closer to the center of the curve travels less distance than the other side of the wheel. The tapering of the wheel allows the wheel to move around the curve without undue motion. However, when moving along straight tracks, the tapering causes the wheel to move back and forth across the tracks. This continues as long as the wheel is turning on a straight track. Depending upon a variety of factors such as the wear of the wheels, the load within the railcar, and the dimensions of the railcar, a railcar can develop a resonant motion which may significantly rock the railcar body. This motion, called “hunting”, can damage goods within the railcar. While systems have been successful in reducing excessive hunting, certain railcars nevertheless have a propensity to develop the resonant motion. These railcars are referred to as “hunters.”
Identifying hunters is difficult. Hunters may only develop the resonant motion at particular speeds or over particular tracks. Visual monitoring by a member of the train crew is therefore difficult.
Hunters may be identified at the conclusion of a journey due to the damage caused to goods carried by the railcars. If goods are not inspected at the time they leave the railcar, there is a possibility that the damage will never be associated with the railcar.
Systems have been proposed to detect hunting. In U.S. Pat. No. 5,622,338, issued to Klink, a truck hunting and detection system is shown. Similarly, in U.S. Pat. No. 5,924,654, issued to Anderson, shows a railroad car sensing system for monitoring car performance which includes a hunting detector.
While such hunting detector systems may be able to detect hunting, they are expensive to manufacture and install. They may require access to an external power source. Retrofitting of railcars currently in service with such a system is extremely difficult. Further, while the systems may accurately record the motion of the car, identification of the hunter by a railroad worker is not easily accomplished.